Gear casing



FIG. 1 is a right perspective view of a gear casing;

FIG. 2 is a left elevation view thereof;

FIG. 3 is a front elevation view;

FIG. 4 is a rear elevation view;

FIG. 5 is another right perspective view thereof; and,

FIG. 6 is a right elevation view. 

CLAIM The ornamental design for a gear casing, as shown and described. 